Vol. 50.] PHYSIOGRAPHY OE THE LIBYAN DESEKT. 539 



Kharga and Selima there is another desert track known as the 

 Terfau road, which runs a little east of south from the village of 

 Mut in the Dakhla Oasis for the first 80 miles or so. Although I 

 could not get as far as the well, several considerations caused me to 

 mark a point ahout 100 miles south of the oasis as the probable 

 site of this well, Bir Abu Tarfa ; and after seeing the geological 

 structure of Bir Murr, the conviction grew that it was situated either 

 on the same anticlinal fold as this latter spring, or on the one passing 

 through Wadi Haifa. A few days later, on meeting an Arab who 

 had travelled this road, the distances that he gave me appeared to 

 confirm the inferred position of this well. 1 



If we prolong the direction of the Bir Murr fold eastward, it is 

 found to cut the Nile just by Korosko, and seems to have been the 

 cause of the river making a sadden bend at this locality, impelling it 

 to work along the fold till the easiest point of crossing it was reached. 

 Passing for a moment to the other desert wells to the south, we 

 find about two days' journey south of Bir Murr a group of wells, 

 known as Kassaba, Nakhlai, and Shebb, the water occurring in each 

 case a few feet from the surface. Between these and the Nile we 

 have the intrusive olivine-dolerite of Jebel Burka, about 20 miles 

 W.N.W. of Wadi Haifa, and about 15 miles down the river from 

 this place a spring runs into the Nile on its western bank, and 

 may be seen trickling over the rocks at low Nile. 



The general direction given by these is slightly more south of east 

 than that of the anticlinal at Bir Murr, but it is difficult to avoid 

 the idea that these springs are due to a similar anticlinal fold, 

 which may also have assisted to bring the Archaean rocks of the 

 Second Cataract to the surface. 



The next wells to the south are those of the Selima Oasis, which 

 is not at present accessible for geological examination, but the map 

 of this region (W.O. Intelligence Map, No. 662) shows to the south 

 of the oasis " 60 miles of alternate ridge and valley," which I 

 believe are the eroded strata of the southern portion of an anticlinal 

 fold, similar to that at Bir Murr, passing through the Selima Oasis. 

 The occurrence 2 of beds of limestone at both these places increases 

 the resemblance. Tbe direction of these ridges is not more south of 

 east than that of the Shebb wells, and, just as we have seen the 

 river deflected by the Bir Murr fold at Korosko, so does it appear 

 possible that the great bend of the Nile between Dongola and Berber 

 may be due to the resistance offered to it by the Selima anticlinal, 

 which turned back the river to wander in the synclinal trough till 

 it found a place to cross in the neighbourhood of the Third Cataract. 

 North of Bir Murr the granite exposure of Jebel Abu Bayan and the 

 springs in the neighbourhood of Beris at the south of the Kharga 

 Oasis form, with the oasis of Kurkur and the exposure of the 

 crystalline rocks at Assuan, another parallel line, and the section 

 published by Zittel 3 shows the presence of an anticlinal curve in 

 Dakhla. I have already pointed out how these folds appear to have 



1 [Recently (June 1894) the well has been found 50 miles W.N.W. of Shebb.] 



2 W. Willcocks, ' Report on Perennial Irrigation and Flood Protection for 

 Egypt/ Cairo, 1894, App. iii. p. 5. 3 Op. jam cit. map. 



